1. Field of the Invention
The present invention relates to a medical device for placement at a predetermined location within a passageway of the human body, and more particularly, relates to a flexible embolization device which may be delivered by a catheter to a pre-selected position within a blood vessel to thereby embolize a blood vessel or a defect in a blood vessel, such as an aneurysm or fistula.
Elongated coil embolization devices are well known in their use to embolize a blood vessel or a defect in a blood vessel such as an aneurysm or fistula, for example a brain aneurysm.
These embolic coils are of small diameter, on the order of 0.012 inch, for example, to have the capability of fitting into small blood vessels. Embolic coils have great advantage over neurosurgical clipping, and are quickly becoming the desired standard of care.
Embolic coils are placed into an aneurysm, which causes clotting to take place in the aneurysm, reducing the risk of aneurysm rupture. The aneurysm becomes protected by the clot, which occupies the volume of the aneurysm. However, a large number of aneurysms tend to recanalize with pressurized blood over time, which once again elevates the risk of aneurysm rupture, or growth of the aneurysm in size, along with causing compaction of the coils.
There is a need for a better, bioactive embolization device. The device of this invention is very flexible to ensure good packing. The device also enhances protein binding and cell attachment, so that the ingrowth of tissue into the aneurysm is encouraged, providing by the presence of living tissue a long-term solution to the problem of recanalization of an aneurysm.
2. Description of the Prior Art
For many years flexible catheters have been used to place various devices within the vessels of the human body. Such devices include dilatation balloons, radiopaque fluids, liquid medications and various types of occlusion devices such as balloons and embolic coils. Examples of such catheter devices are disclosed in U.S. Pat. No. 5,108,407 to Geremia, et al., entitled “Method and Apparatus for Placement of an Embolic Coil” and U.S. Pat. No. 5,122,136 to Guglielmi, et al., entitled “Endovascular Electrolytically Detachable Guidewire Tip for the Electroformation of Thrombus in Arteries, Veins, Aneurysms, Vascular Malformations and Arteriovenous Fistulas.” These patents disclose devices for delivering embolic coils at predetermined positions within vessels of the human body in order to treat aneurysms, or alternatively, to occlude the blood vessel at a particular location.
Elongated, embolic coils, which are placed in vessels, may take the form of helically wound coils, or, alternatively, may be random wound coils, coils wound within other coils or other such coil configurations. Examples of various coil configurations are disclosed in U.S. Pat. No. 5,334,210 to Gianturco, entitled, “Vascular Occlusion Assembly” and U.S. Pat. No. 5,382,259 to Phelps, et al., entitled, “Vasoocclusion Coil With Attached Tubular Woven or Braided Fibrous Coverings.” Embolic coils are generally formed of radiopaque material, such as platinum, gold, tungsten or alloys of these metals. Often times several coils are placed at a given location in order to occlude the flow of blood through the vessel by promoting thrombus formation at the particular location.
In the past, embolic coils have been placed within the distal end of a catheter, and when the distal end of the catheter is properly positioned the coil may then be pushed out of the end of the catheter with, for example, a guidewire, to release the coil at the desired location. This procedure for placement of the embolic coil is conducted under fluoroscopic visualization such that the movement of the coil through the vasculature of the body may be monitored, and the coil may be placed in the desired location.
Other embolization devices, such as detachable balloons, are placed in blood vessels or aneurysms. These balloons usually take the form of an inflatable, elastic balloon with a valve assembly for sealing the balloon when a desired inflation is reached. Examples of various detachable balloons are disclosed in U.S. Pat. No. 4,517,979 to Pecenka, entitled, “Detachable Balloon Catheter” and U.S. Pat. No. 4,545,367 to Tucci, entitled “Detachable Balloon Catheter and Method of Use.” Detachable balloons are generally formed of a flexible polymer and are inflated with a radiopaque solution for visualization under fluoroscopy. Often several balloons are used to fill the aneurysm space. These balloons do not generally conform to the aneurysm space, thereby leaving unoccupied space leading to an incomplete aneurysm embolization. Often times a balloon valve may leak, thereby causing other balloons to shift position, which may, in turn, occlude the parent artery, leading to severe complications.